Microcontroller based data acquisition and control of a solar thermal energy system.

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Abstract

A solar thermal energy system is being rebuilt at University of KwaZulu-Natal School
of Physics. A similar system is also being built in the University Eduardo Mondlane –
Maputo Mozambique, in a team development work. The system is composed
mainly of the following subsystems:
(i) An Energy capture subsystem: paraboloidal dish concentrator with a heat
receiver, mounted on a dual axis polar mount sun tracking assembly;
(ii) An Energy storage subsystem: rock-bed thermal energy storage (TES) system;
(iii) An Energy utilization subsystem: any user heat utilization (like a cooking or
water boiling appliance); and
(iv) A monitoring and control subsystem.
The subsystem (iv) for performing a controlled charging of the Thermal Energy
Storage from a hot plate simulated solar heat, was formerly developed and it was
based on 2 conventional data loggers (HP/Agilent) and programs running on 2 PCs.
The present work is aimed at performing the same plus additional monitoring and
control tasks, based on a low cost microcontroller design. The monitoring and
control subsystem based on the Atmel ATmega 32 MCU has been designed and
built, capable of performing data acquisition, data logging and control of relevant
system variables such as, hour and declination angles of the tracking concentrator;
to cite some of the main variables.
Besides a huge work of designing, building, programming and testing the
microcontroller system itself, a special focus was given to the monitoring and
control of the solar heat concentrator, to perform a dual axis sun tracking, so as to
get as much as possible of the available solar radiation. Measurements of various
system parameters such as, the sun tracking actual hour and declination angles,
the inlet and outlet temperatures of both the heat receiver and the rock bed heat
storage, etc., for the system under consideration have been carried out.